C. Eckardt

Reactions with polarized electrons and photons at low momentum transfers at the superconducting Darmstadt electron linear accelerator S-DALINAC

A source of polarized electrons has been installed at the superconducting Darmstadt electron linear accelerator S-DALINAC. Experiments with polarized electrons from 100 keV to about 80 MeV are expected to commence in early 2011. This contribution summarizes the status of the polarized source as well as ongoing preparations for the experimental program with polarized beams. In particular, we present results on unpolarized test experiments of the 234,238 U(γ,f) reactions and considerations for the 2 D(� e,ep) and 3 He(� e,ep) reactions.

Status and recent developments at the polarized-electron injector of the superconducting Darmstadt electron linear accelerator S-DALINAC

At the superconducting Darmstadt electron linac a 100 keV source of polarized electrons has been installed. Major components had been tested prior to installation at an offline teststand. Commissioning of the new source at the S-DALINAC will take place early in 2011. We report on the performance of the teststand, simulations, developments on the laser systems, new radio-frequency components for the S-DALINAC injector, and the status of the implementation of the source.

Polarized Electrons in Darmstadt: Recent Developments

The injector of the superconducting Darmstadt electron linear accelerator S‐DALINAC will soon be extended by a source of polarized electrons. A test set‐up of the future source consists of a 100 keV GaAs polarized gun and associated beamline including an assembly for polarization manipulation and determination. We give a short overview of the existing and planned polarimeters at the different accelerator sites, introduce briefly the future implementation of the polarized source at the S‐DALINAC and list experiments that are planned with polarized electron and photon beams.

Status Report of the New Darmstadt Polarized Electron Injector

We present the status of the polarized injector for the superconducting Darmstadt electron linear accelerator S‐DALINAC. An offline teststand of the source was built to test all components of the S‐DALINAC polarized injector SPIN. The new electron source will deliver a 100 keV polarized beam and complement the present thermionic source operating at 250 kV. Results of the beam properties measurements will be introduced and an outlook on the upcoming installation of the new injector at the S‐DALINAC will be given.

RECENT RESULTS FROM PHOTON-INDUCED FISSION EXPERIMENTS AT THE S-DALINAC

Bremsstrahlung with endpoint energies slightly above the fission barrier is produced from stopping an electron beam in a thick copper target. Mass, total kinetic energy (TKE) and angular distribution of the fission fragments were determined by means of the double kinetic energy technique, using a twin Frisch-grid ionization chamber. First results on angular distributions and their correlations with mass and TKE of the fragments as well as an analysis within the fission-mode concept of the multi-modal random neck-rupture model by Brosa et al.[2], are presented [3]. It is shown that the emission angle of the fission fragments can be extracted from an electron drift-time measurement [4] and that the target thickness influences the experimental results [5].

ELECTRON BEAM POLARIMETRY AT LOW ENERGIES AND ITS APPLICATIONS

Low energy (E-k similar to 100 keV) Mott scattering polarimetry is a widely established technique to measure the polarization of an electron beam. We analyze the feasibility of Mott scattering at e ...

Polarized Electrons for Experiments at Low Momentum Transfer SPIN @ S‐DALINAC

The superconducting Darmstadt linear electron accelerator S‐DALINAC will be expanded by a newly developed polarized injector concept called SPIN. The polarized beam program includes experiments to search for parity violation in photo induced fission, the investigation of the 5th structure function at low momentum transfer and break up reactions of few body systems. These experiments and an overview of the current experiemental program will be covered in this paper.

Polarimetry at the Superconducting Darmstadt Electron Linac S‐DALINAC

A spin polarized electron source will be installed at the S‐DALINAC to extend the existing experimental capabilities polarization. In order to manipulate and monitor the beam polarization a Wien filter and different polarimeters will be installed. The already installed Wien filter and 100 keV Mott polarimeter and the planned 5 MeV Mott, 30–130 MeV Mo/ller and Compton transmission polarimeters are described.

Photo‐fission at the S‐DALINAC

Experiments on photo-induced fission of 238U and 234U using bremsstrahlung with endpoint energies between 6 MeV and 9 MeV have been carried out at the superconducting Darmstadt electron linear acce ...